The Circumboreal Region is a floristic region within the Holarctic Kingdom in Eurasia and North America, as delineated by such geobotanists as Josias Braun-Blanquet and Armen Takhtajan.

It is the largest floristic region in the world by area, comprising most of Canada, Alaska, Europe, Caucasus and Russia, as well as North Anatolia (as the southernmost part of the region) and parts of northern New England, Michigan, and Minnesota. Northern portions of the region include polar desert, taiga and tundra biomes. Many geobotanists divide the Eurasian and North American areas into two distinct regions. The continents, however, share much of their boreal flora (e.g. Betula nana, Alnus viridis, Vaccinium vitis-idaea, Arctostaphylos uva-ursi). The flora was severely impoverished during glaciations in the Pleistocene. The region is bordered by Eastern Asiatic, North American Atlantic, Rocky Mountain, Mediterranean and Irano-Turanian Regions.

There are no biological families endemic to this region, but it has endemic genera (e.g. Lunaria, Borodinia, Gorodkovia, Redowskia, Soldanella, Physospermum, Astrantia, Thorella, Pulmonaria, Erinus, Ramonda, Haberlea, Jankaea, Stratiotes, Telekia) and a lot of endemic species, especially in the mountains.